Remember that you can use the OutSystems debugger to inspect how your code is being executed. You can do that by simply running your eSpace and adding your personal testing area to the URL that you invoke. This way you can easily find out what is wrong seeing your flow executing step-by-step.

In case you are accessing an entry point with the name MyEntry in an eSpace with the name MyEspace and your username in Service Center is Filipe, all you have to do to be able to debug your screen is:

Run your eSpace (MyEspace) while logged in to the OutSystems platform with the user Filipe;

By doing this, once your screen is invoked, you will see it executing in Service Studio (it will stop in the break point in the preparation of your screen). Now, just use the debugger to see how it executes and inspect the variable values. See the video at Debug Applications Visually.